Detergent composition



United States Patent 3,324,038 DETERGENT CGMPOSITION Robert Hornet Chaifee, Westfield, N.J., and Larry Edward Meyer, Cincinnati, Ohio, assignors to Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Apr. 17, 1964, Ser. No. 360,734 11 Claims. (Cl. 252152) This invention pertains to detergent compositions in' the form of fast-dissolving tablets prepared by compressing detergent particles together.

Specifically, this invention relates to coated detergent tablets having good strength and good resistance to surface abrasion which dissolve rapidly in water to form aqueous detergent solutions.

Fast-dissolving detergent tablets prepared by compressing detergent particles are well known and are convenient to use. In order to have a suitable detergent tablet of this type the detergent tablet must be strong and have a surface which is resistant to abrasion and yet the tablet must disolve quickly in water. The first two of these qualities usually require processing conditions which tend to increase the time it takes to dissolve the tablet in water. It has been previously suggested that such tablets can be coated with materials to increase the strength and abrasion resistance of such tablets without materially increasing the dissolving time. The coatings suggested have normally been detergent adjuvants.

It is therefore an object of this invention to provide a new improved coating material for detergent tablets prepared by compressing detergent particles.

It is also a more specific object of this invention to provide improved coatings comprising detergent actives.

It is another object of this invention to provide detergent tablets covered with said coating materials which are strong, abrasion resistant and quick dissolving.

The preceding objects and other objects can be achieved by providing a detergent composition comprising a coated detergent tablet core prepared by compressing detergent particles, said tablet having a substantially uniform coating comprising a composition prepared from (1) urea and (2) a material selected from the group consisting of (a) Polyethylene glycol having an average molecular weight of from 500 to 10,000;

(b) Water soluble detergent surfactant having a long straight chain of at least carbon atoms in its molecular structure; and

(c) Mixtures thereof;

the ratio of said urea to said material being in the range from about 1:1 to about 9:1 and there being from .005 to 0.1 grams of coating material per square centimeter of tablet surface on an anhydrous basis.

In order to prepare a coated tablet of this invention, one must first prepare a conventional detergent tablet, i.e., tablet core, by means of compressing detergent particles. A strong tablet core can be produced by compressing particulate detergent matter using high pressures. However, high pressure creates a tablet which does not dissolve easily. Therefore, the tablets used to make cores for the coated tablets of this invention are normally com pressed at a pressure of from 100 to 350 or 450 p.s.i.g.

The particulate form used in preparing the tablet cores of this invention is not critical. For examples, granules, flakes, needles and beads can all be used. Non-particulate forms, however, such as pastes and liquids, are not acceptable as tablet components in any appreciable amount since they will rearrange in the tablet core causing stickiness and slow dissolving rates. The detergent surfactants used in forming the particles which make up the bulk of "ice the tablet core can be any detergent surfactant which can be made in normally particulate form by drying or cooling, e.g., either alone or in combination with any of the other tablet constituents. The detergent surfactants can be soap, anionic non-soap, nonionic, ampholytic or zwitterionic. At least 5% by weight of the tablet core should be detergent surfactant in order to provide a tablet of suitable size having a suitable concentration of detergent surfactant for Washing purposes. More than 30% by weight of the detergent surfactant in the tablet core will lead to an excessively sticky tablet and this in turn will lead to a deficiency of interparticulatevoids, thereby preventing the water from diffusing through the tablet core to dissolve said tablet.

The particle size of the particles of detergent surfactant used in preparing the tablet core should not be more than about 6 mesh and not less than about mesh. This size range is equivalent to particles which, when screened on Tyler screens, will be on 100 mesh and through 6 mesh. Particles larger than 6 mesh make it diflicult to mechanically incorporate uniformly other constituents because of the diameter ratios and particles smaller than 100 mesh promote segregation of the detergent surfactant particles from other particles and slow dissolving rates by blocking interparticulate voids which serve as penetration routes for the water.

The particulate detergent used in the tablet core should not contain more than about 10% by weight of the detergent as free water. Too much free water causes stickiness which prevents the particles from being free flowing and thereby prevents the formation of a satisfactory tablet core. Tablet cores formed with an excess of free water have a deficiency of interparticulate voids and, therefore, have a slow dissolving rate.

A particulate detergent used in the tablet core having less than about 1% by weight of free water produces a very brittle tablet core because the particles are so crisp that little bonding between particles is possible.

Examples of detergent surfactants which can be used in the tablet core include:

1) Ordinary alkali metal soaps ,such as the sodium and potassium salts of the higher fatty acids of naturally occurring plant or animal esters (e.g., palm oil, coconut oil, babassu oil, soybean oil, castor oil, tallow, whale andfish oils, grease and lard, and mixtures thereof) or of synthetically produced fatty acids (e.g., rosin and those resin acids in tall oil) and/or of naphthenic acids. Sodium and potassium soaps can be made by direct saponification of the fats and oils or by the neutralization of the free fatty acids which are prepared in a separate manufacturing process.

2) Synthetic organic detergents characterized by their high solubility in water, their resistance to precipitation by the constituents of hard water and their surface active and effective detergent properties, including:

(a) Anionic synthetic deter ents (excluding true soaps) .This class of synthetic detergents can be broadlv described as the water-soluble salts, particularlv the alkali metal salts, of organic sulfuric reaction products having in the molecular structure an alkyl radical containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. Important examples of the synthetic detergents which form a part of the preferred compositions of the present invention are the sodium or potassium alkyl sulfates, especially those obtained by sulfonating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium or potassium alkyl benzene sulfonates, in which the alkyl group in a straight or branched chain contains from about 9 to about 15 carbon atoms, especially those of the types described in United States Letters Patent Numbers 2,220,- 099 and 2,477,383; sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of sulfuric acid esters of the reaction product of one mole of a higher fatty alcohol (e.g., tallow or coconut oil alcohols) and about three moles of ethylene oxide; sodium or potassium salts of alkyl phenol ethylene oxide ether sulfates with an average of about four units of ethylene oxide per molecule and in which the alkyl radicals contain about 9 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil; sodium or potassium salts of fatty acid amide of a methyltaurine in which the fatty acids, for example, are derived from coconut oil; and others known in the art, a number being specifically set forth in United States Letters Patent Numbers 2,486,921, 2,486,922 and 2,396,- 278.

(b) Nonionic synthetic detergents.-This class of synthetic detergents can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which can be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a watersoluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

For examples, a well known class of nonionic synthetic detergents is made available on the market under the trade name of Pluronic. These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The hydrophobic portion of the molecule which, of course, exhibits water insolubility has a molecular weight of from about 1500 to 1800. The addition of polyoxyethylene radicals to this hydrophobic portion tends to increase the water solubility of the molecule as a whole and the liquid character of the products is retained up to the point where polyoxyethylene content is about 50% of the total weight of the condensation product.

Other suitable nonionic synthetic detergents include:

(i) The polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing from about 6 to 12 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the said ethylene oxide being present in amounts equal to to 25 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be derived from pclymerized propylene, diisobutylene, octane, or nonane, for example.

(ii) Those derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine-products which can be varied in composition depending upon the balance between the hydrophobic and hydrophilic elements which is desired. For examples, compounds containing from about 40% to about 80% polyoxyethylene by weight and having a molecular weight of from about 5000 to about 11,000, resulting from the reaction of ethylene oxide groups with a hydrophobic base constituted of the reaction product of ethylene diamine and excess propylene oxide, said base having a molecular weight of the order of 2500 to 3000, are satisfactory.

(iii) The condensation products of aliphatic alcohols having from 8 to 18 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide, e.g., a coconut alcohol ethylene oxide condensate having from 10 to 30 moles of ethylene oxide per mole of coconut alcohol, the coconut alcohol fraction having from 10 to 14 carbon atoms.

(0) Long chain tertiary amine oxides corresponding to the following general formula, R R R N+O, wherein R is an alkyl radical of from about 8 to about 18 carbon atoms, and R and R are each methyl or ethyl radicals. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of amine oxides suitable for use in this invention include dimethyldodecyl amine oxide, dimethyloctylamine oxide, dimethyldecylamine oxide, dimethyltetradecylamine oxide, dimethylhexadecylamine oxide.

((1) Long chain tertiary phosphine oxides corresponding to the following general formula RRR"P- O wherein R is an alkyl, alkenyl or monohydroxyalkyl radical ranging from 10 to 18 carbon atoms in chain length and R and R are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbon atoms. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of suitable phosphine oxides are:

Dodecyldirnethylphosphine oxide, Tetradecyldimethylphosphine oxide, Tetradecylmethylethylphosphine oxide, Cetyldimethylphosphine oxide, Stearyldimethylphosphine oxide, Cetylethylpropylphosphine oxide, Dodecyldiethylphosphine oxide, Tetradecyldiethylphosp-hine oxide, Dodecyldipropylphosphine oxide, Dodecyldi(hydroxymethyl) phosphine oxide, Dodecyldi(2-hydroxymethyl) phosphine oxide, Tetradecylmet-hyl-Z-hydroxypropyl phosphine oxide, Oleyldimethylphosphine oxide, and Z-hydroxydodecyldimethylphosphine oxide.

(e) Long chain dialkyl sulfoxides containing one short chain (usually methyl) and one long hydrophobic chain which can contain ether linkages, keto groups, and hydroxy groups and which contain from about 10 to about 20 carbon atoms. Examples include:

Octadecyl methyl sulfoxide,

Dodecyl methyl sulfoxide,

Tetradecyl methyl sulfoxide, 3-rnethoxytridecyl methyl sulfoxide, 3-hydroxytridecyl methyl sulfoxide, 3-hydroxy-4-dodecoxybutyl methyl sulfoxide.

(f) Ampholytic synthetic detergents can be broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Examples of compounds falling within this definition are sodium 3- -dodecylaminopropionate, sodium 3-dodecylaminopropane sulfonate, dodecyl-beta-alanine, N-alkyltaurines such as the one prepared by reacting dodecylamine with sodium isethionate according to the teaching of U.S. 2,658,072,

"N-higher alkyl aspartic acids such as those produced acwhich are especially preferred for their excellent cool water detergency characteristics.

The alkyl groups contained in said detergent surfactants can be straight or branched and saturated or unsaturated as desired. The above list of detergent surfactants is exemplary and not limiting. Mixtures of the above detergent surfactants can be used.

In addition to the detergent surfactant used in the tablet cores which are formed into the coated tablets of this invention, other constituents can be used as hereinbefore mentioned. Detergency builders of inorganic and organic types are a highly desirable constituent. Not only do they aid detergency, but in the case of the inorganic builders they promote the formation of suitable tabletable particles when the detergent surfactant itself does not readily form particles. The builder can make up the balance of the tablet core (up to about 95% by weight of the tablet core); however, when the inorganic builders are used, high levels tend to cause brittleness of the tablet, thereby decreasing the tablets strength. Preferably inorganic builders comprise from about to about 75% of the tablet core. When lower levels of inorganic builders are used the amount of diluents, e.g., inert inorganic salts, is normally higher.

The builder can be added separately in particulate form or formed into particles with the detergent surfactant and/or the other constituents as hereinafter described. If added separately, the builder particle size should not be larger than about 14 mesh or smaller than about 200 mesh. Particles larger than 14 mesh are not very soluble and particles smaller than 200 mesh tend to separate from particles of other constituents and block interparticulate voids.

Examples of water soluble inorganic alkaline detergency builder salts are alkali metal carbonates, phosphates, polyphosphates, and silicates. Specific examples of such salts are sodium and potassium tripolyphosphates, carbonates, pyrophosphates, phosphates, and hexametaphosphates. Examples of organic alkaline sequestrant builder salts are (1) alkali metal amino polycarboxylates [e.g., sodium and potassium ethylene diaminetetraacetates, N- (Z-hydroxyethyl)-ethylene diamine triacetates, nitrilo triacetates, and N-(Z-hydroxyethyl)-nitrilo diacetates]; (2) alkali metal salts of phytic acid (e.g., sodium and potassium phy-tates, see US. Patent 2,739,942); (3) water soluble salts of ethane-1-hydroxy-1,l-diphosphonate (e.g., the trisodium and tripotassium salts); (4) Water soluble salts of methylene diphosphonic acid (e.g., trisodium and tripotassium methylene diphosphonate and the other salts described in the copending application of Francis L. Diehl, Ser. No. 266,025, filed Mar. 18, 1963 now US Patent 3,213,030); (5) water soluble salts of substituted methylene diphosphonic acids (e.g., trisodium and tripotassium ethyl-idene, isop-ropylidene, benzylmethylidene, and halomethylidene diphosphonates and the other substituted methylene diphosphon-ates disclosed in the copending application of Clarence H. Roy, Ser. No. 266,055, filed Mar. 18, 1963); (6) water soluble salts of polycarboxylate polymers and copolymers as described in the copending application of Francis L. Diehl, Ser. No. 269,359, filed Apr. 1, 1963 (e.g., polymers of itacon-ic acid; aconitic acid; maleic acid; mesaconic acid; fumaric acid, methylene malonic acid; and citronic acid and copolymers with themselves and other compatible monomers such as ethylene; and (7) mixtures thereof.

Mixtures of or-ganicand/ or inorganic builders can be used and are generally desirable. Especially preferred are the mixtures of builders disclosed in the copending application of Burton H. Gedge, Ser. No. 235,327 now abandoned, filed Nov. 5, 1962, e.g., ternary mixtures of sodium tripolyphosphate, sodium nitrilotriacetate, and sodium ethane-l-hydroxy-l,l-diphosphonate.

Other minor ingredients can also be added to the tablet cores used to form the coated tablets of this invention (e.g., added to the particulate mixture prior to compression). Soil suspending agents such as carboxyrnethylcellulose, optical brighteners, sodium and potassium silicates, diluents such as sodium sulfate and sodium chloride, dye and benzotriazole can be added. The total amount of these minor ingredients is preferably less than 10% by weight of the tablet. Normally they are formed into particles with the detergent surfactant.

The coated tablets of this invention are characterized by a coating which is prepared from urea and either polyethylene oxide having a molecular weight of from about 500 to about 10,000, preferably 3,000 to 7,500, or a water soluble detergent surfactant having a long straight chain in its molecular structure. It is believed that the urea forms adducts with such detergent surfactants.

Examples of detergent surfactants which are suitable for use in the coating, include water soluble salts of alkyl sulfates wherein the alkyl group contains from about 12 to about 18 carbon atoms; the reaction product of one mole of a straight chain alcohol containing from about 12 to about 18 carbon atoms and from about 8 to about 250 moles of ethylene oxide; the condensation product of one mole of an alkyl phenol wherein the alkyl group contains from about 8 to about 15 carbon atoms with from about 8 to about 250 moles of ethylene oxide; polyethylene glycols having from about 10 to about 250 moles of ethylene oxide; and a compound having the formula wherein the R alkyl contains from about 12 to about 18 carbon atoms and the R and R alkyls each contain from about 1 to about 3 carbon atoms. As mentioned hereinbefore, the ratio of urea to the above surfactants is in the range from about 1:1 to about 9:1. If the ureazsnrfactant ratio is higher than about 9:1, the coatings resistance to humid conditions is lessened to a point where it is difficult to obtain acceptable coatings. All ratios herein are by weight unless otherwise specified.

The above coating can be applied to the surface of the tablet in several ways. For example, a preferred method of coating involves preparing an aqueous mixture (preferably a solution) of the coating materials in which the ratio of water to coating material can range from about 3:1 to about'1:2.5 by weight'A ratio of from about 1:1 to about 1:15 is preferred. The temperature of the aqueous mixture is preferably held at a sufliciently high temperature to make the solution a single phase. The temperature, however, should not exceed 210 F. since the water evaporates very rapidly at higher temperatures. The above aqueous mixture or solution can be either sprayed in the form of small droplets on the surface of the tablet core or the tablet core can be dipped into the aqueous mixture of solution. When the tablet is dipped, the tablet should not remain in the mixture or solution for more than about 2 /2 seconds to prevent excessive solution of the tablet ingredients and excessive application of coating material. Temperatures of from about F. to about F. are satisfactory for the application of the aqueous solution. The inclusion of a drying step after the application of the aqueous mixture is a preferred variation. This drying step can comprise, e.g., radiant heat or a blast of hot air giving a temperature of from about 150 F. to 250 F. for a period of from about five seconds to about two minutes. Preferably the tablets are cooled after the drying step to about room temperature, e.g. by a blast of cool air.

The tablets can also be coated by preparing a melt of the e.g., urea-polyoxyethylene or urea-surfactant mixtures. A temperature of from about 275 F. to about 350 F. is suitable for making an anhydrous molten mixture. As with the aqueous mixtures, the molten material can be either sprayed onto the surface of the tablet core or the tablet core can be dipped into the molten material. A

preferred variation includes an additional step in which the coated tablet is cooled to below the solidification temperature of the melt, preferably to around room temperature, e.g., by a blast of cool air.

As herein-before discussed, the coating should be applied in an amount from about .005 to 0.1 gram per square centimeter of tablet core surfaces on an anhydrous basis. The preferred amount of coating is from about .025 to about .075 gram per square centimeter of tablet core surface area of an anhydrous basis. This level of coating essentially eliminates the problem of tablet surface abrasion during handling and packaging and strengthens the tablet while increasing the tablet dissolving time only to a very slight degree, it at all. The coated tablet is resistant to abrasion and has a smooth, desirable appearance.

The following examples illustrate, but do not limit the practice of this invention. All percentages and parts herein are by weight unless otherwise specified.

Example I A mechanical mix was prepared having the following composition.

Added as a spray dried detergent:

Parts Tetrapropylene benzene sulfonate, sodium salt 10.5 Sodium tripolyphosphate (STP) 2.0:1 (SiO :Na O) ratio silicate solids 7.5 Water (free and combined) 4 Ethylene oxide condensed on a propylene oxide: propylene glycol base (molecular weight 2900) This mechanical mix was compressed into tablet cores with maximum diameters of 5.71 centimeters and with a pressure of about 150 p.s.i.g. The tablet cores edges were beveled on a 30 angle from the flat sides and starting in. from the axis of the tablet. As used hereinafter, beveled on a 30 angle will refer to this type of bevel. The tablet cores weighed approximately 54 grams and had surface areas of about 80 square centimeters. The finished tablets had densities of about 1.02 gms./cc. and maximum thicknesses of about 2.49 centimeters.

These tablet cores were uniformly coated by dipping them for 1 to 2 seconds in a solution at about 170 F. containing 50% urea, 40% water, and 10% of the condensate of one mole of nonylphenol and 100 moles ethylene oxide. About 2.94 grams of solution adhered to the tablet cores, providing about .02 gram of coating per square centimeter on an anhydrous basis. The tablets were allowed to dry at room temperature.

The coated tablets had an improved strength, resistance to abrasion, humidity resistance and an excellent appearance. These coated tablets had an acceptably low dissolving time. Without the coating, these tablets were not sufficiently strong to withstand normal shipping and handling, but after coating they were sufficiently strong.

Example 11 60 parts granular STP, ranging in particle size from about 14 to about 200 mesh, were hydrated by spraying on 18 parts water, 7.3 parts of 2.011 (SiO :Na O) ratio granular hydrated silicate, ranging in particle size from about 14 to about 200 mesh and parts of sodium tallow alkyl sulfate flakes having a thickness of from about 5 to 15 thousandths of an inch and containing about 61.8% active, about 31.2% Na SO about 2% water and about 5% unreacted organic material were mechanically mixed with the hydrated STP. 4.7 parts of Igepal DM710, which is a condensate of one mole of a dialkyl (C phenol, and 15 moles of ethylene oxide were sprayed onto the above mechanical mix.

The mix was tableted at a pressure of about 450 p.s.i.g., and the tablet cores had a maximum diameter of 5.71 centimeters. The tablet edges were beveled on a 30 angle. The tablet cores weighed approximately 57 grams and had a maximum thickness of about 2.48 centimeters.

The coating solution was made of 45% urea, 40% water and 15% of the condensate of one mole of nonyl phenol and 30 moles of ethylene oxide.

The tablet cores were immersed for l2 seconds in the coating solution having a temperature of about F. and this gave a uniform coating of about 3 grams per tablet on a solution basis. The coated tablets had a surface area of about 80 square centimeters, providing about .04 gram of coating per square cm.

The coated and uncoated tablets of this example were tested by subjecting them to a crushing test (Mullen); the point at which the tablet collapses being measured in pounds per square inch; an impact test in which a standard weight of 800 grams, of which 176 grams was the pendulum rod, was allowed to swing on a pendulum with a total length of 39 and inches through the tablet so that a free swing was 45 past the point of impact, the number of degrees of continuation of the swing being inversely related to the strength of the tablet; and a dissolving test (TOD) in which the time it takes a tablet to dissolve in mildly agitated 100 F. water was determined. The results were as follows:

Mullen Impact TOD 100 F.

(p.s.i.g.) (degree) (sec.)

Uneoat ed 47 36 148 Coated 84 20 198 61.8 parts of a 0.7 gms./cc. bulk density particulate sodium tripolyphosphate and 7.7 parts of a particulate hydrated 2.0:1 (SiO :Na O) ratio silicate were mechanically mixed and agglomerated to particles of from about 6 to about 100 mesh with 18.5 parts of a 2% aqueous solution of sodium carboxymethylcellulose. 12 parts of a condensate of one mole of dodecyl phenol and about 8 moles of ethylene oxide was applied to the agglomerate. About 59 gm. of this mix was tableted at a pressure of about 300 psi. to a thickness of about 2.49 cm. with a maximum diameter of about 5.71 cm. to form tablet cores. The edges were beveled on a 30 angle.

The above ta'blet cores were coated by immersing them in an aqueous solution containing about 40% water, about 50% urea and about 10% of a condensate of one mole of nonyl phenol and 100 moles of ethylene oxide. In about one second of immersion at F., sufficient solution adhered to the tablet surface to provide about .03 gm./cm. of uniform coating on an anhydrous basis, thereby increasing the thickness of the tablet by about 0.04 cm. The coating crystallized On the surface of the tablet to produce a smooth, non-abradable, humidityresistant surface. These coated tablets were sufliciently strong to withstand the rigors of ordinary shipping and handling and dissolved quickly in water. Their strength was improved as compared with uncoated tablets and the dissolving time was about the same for both coated and uncoated tablets.

This mechanical mix was then agglomerated by spraying on an agglomerating mixture of 1-2.6 parts of a aqueous solution of sodium carboxymethyl cellulose; 4.1 parts of a dodecyl phenol ethylene oxide (8 moles) con- Parts Sodium tripolyphosphate 10.0 Trisodium nitrilotriacetate 9:0 Tetrasodium pyrophosphate 2.0 Trisodium phosphate 1.0 Sodium ethane-l-hydroxyl,l-diphosphonate 9.0 Sodium silicate (1.6:1 siO zNa O) 7.5 Sodium sulfate 8.0 Sodium carboxymethyl cellulose and dyes 0.8 Water (free and combined) 4.7

The particle size distribution (Tyler standard screen) of this spray dried detergent is about as follows:

densate; and 4.1 parts of a nonyl phenol ethylene oxide screen size 10 100 (8 moles) condensate, The bulk density of the agglomerates was about 0.72 gm./ cc. and the particle size dis- Cumulativemmem 10 40 99 tribution (Tyler standard screen) was about as follows:

Screen Size B, On 14 On 20 I On 28 On 35 On 48 On 65 On 100 Cumulative, percent n, 29.4 I 47.5 I 69.2 83.6 92.4 97.0 99.8

These agglomerates were used to form tablet cores by The granular tripolyphosphate has a particle size rangcompressing about 59 gm. of the agglomerates to a thicking from 14 to 100 mesh. ness of about 2.35 cm. at a pressure of about 250 p.s.i. The bulk density of this tablet mix is about 0.5 gm./cc. with a maximum diameter of about 5.71 cm. The edges This mix is tableted at about 250 p.s.i. to prepare tablet were beveled on a angle. 30 cores having a Weight of from about 51 gm. to about 55 The above described tablet cores were coated by imgm. having a thickness of about 2.50 cm. These tablet mersing them from about one half of a second in an cores have a maximum diameter of about 5.71 cm. and aqueous solution at 170 F. containing about 37% water, the edges ar b veled on a 30 angle, about 23% Y alkylammonio)- When (1) sodium or potassium coconut and/or tallow 2"hydroxy propane-l-slllfona'to Y Y Sultaino) and soaps; (2) coconut alkyl dimethyl amine oxide; (3) about 40% urea. Suflicient solution was added to the tabdodecyl dimethyl phosphine oxide; (4) 3-hydroxy 4 Surfaco to give about gITL/ 6111-2 of uniform coat" dodecoxybutyl methyl sulfoxide; or (5) sodium or potasl'Ilg of an anhydrous basis- The tablet was then Partially sium N-coeonut alkyltaurine are substituted, either comdried With a blast of hot air at about 200 F., fOllOWfid pletely or in part, for the detergent active system in the y a blast of Cold at about Which ofystamlod 40 above granules so as to form similar granules, substanthe coating on the tablet surface. The coated tablets were strong, had a smooth surface and dissolved quickly in water.

Similar results are obtained in strengthening the tablet cores without appreciably increasing dissolving times of the tablets when the above tablet cores are uniformly coated in the same manner as in Example IV with aqueous solutions containing the following and in which the balance of the solution is water:

The above coated tablets have smooth, uniform coatings that are soluble, non-abradable, and non-sticky.

Example V A tablet mix is prepared by mechanically mixing 68 parts of spray dried detergent and 32 parts of granular anhydrous sodium tripolyphosphate. The composition of the spray dried detergent is as follows:

Parts Sodium alkyl (C -C mixture) sulfate 6.0 Sodium dodecyl benzene sulfonate 5.0 Dodecyl dimethyl amine oxide 3.0

Lauryl alcohol (one mole) ethylene oxide (5 moles) condensate 2.0

tially the same results are achieved in that the resulting detergent tablet cores can be improved by the coatings hereinafter described.

The above tablet cores are coated uniformly by the following processes. The undefined balance of each coating solution is water.

(1) Sufficient aqueous solution containing about 33% polyethylene glycol of a molecular weight of about 4000 and about 34% urea is sprayed onto the tablet core at a temperature of about 185 F. to give 0.017 gm./cm. of coating on an anhydrous basis. A blast of hot air at about 200 F. drives off the excess water and a subsequent blast of cold air at 60 F. crystallizes the coating on the tablet surface.

(2) Using the solution of process 1 at a temperature of about C., the tablet cores are coated with sufficient solution, by dipping them in the solution for about 1 second, to give 0.025 gm./cm. of coating on an anhydrous basis. The resulting coating is more uniform than the coating of process 1.

(3) The tablet cores are dipped in an anhydrous melt at about C. whose composition is 75% urea and 25% nonyl phenol (one mol) ethylene oxide (8 moles) condensate to give, after cooling and solidification, a coating of about 0.08 gm./cm.

(4) The tablet cores are sprayed with the melt of process 3 at a temperature of about C. to give, after cooling and solidification, about 0.025 gm./cm. of coating.

(5) The tablet cores are immersed in an aqueous solution at about F. and containing about 59% urea and about 7% C C fatty alcohol mixture (one mole) ethylene oxide (10 moles) condensate, to give, after drying and cooling, about 0.01 gm./cm. of coating on an anhydrous basis.

1 1 The coated tablets prepared by the above processes are smooth, abrasion-resistant, humidity-resistant, strong and quick-dissolving.

Example V1 Spray dried granules of the following composition are used in preparing a tablet mix.

Parts Sodium linear alkylate (C C mixture) sulfonate 4.5 Sodium alkyl (C -C mixture) sulfate 5.5

Fatty alcohol (one mole; C C mixture ethylene oxide (10 moles) condensate 2.0 Hydroxy sultaine (see Example IV) 4.0 Sodium tripolyphosphate 18.0 2.0:1 (SlO INH O) ratio sodium silicate 7.0 Sodium sulfate 13.2 Water (free and combined) 5.0 Sodium carboxymethyl cellulose and dyes 0.8

Total 60.0

The above spray dried granules have a bulk density of about 0.40 gm./ cc. the particle size distribution (Tyler standard screen) is as follows:

Screen Size 10 14 20 35 100 Cumulative, percent 8 25 50 80 99 60 parts of the above spray dried granules are mechanically mixed with the following builder systems having particle sizes ranging from 14-100 mesh.

(1) 40 parts sodium tripolyphosphate.

(2) 30 parts sodium tripolyphosphate and 10 parts trisodium nitrilotriacetate monohydrate.

(3) 25 parts sodium tripolyphosphate, 5 parts tetrasodium pyrophosphate, 5 parts sodium nitrilotriacetate monohydrate, and 5 parts of the tetra sodium salt of ethylenediaminetetraacetic acid.

(4) 30 parts sodium tripolyphosphate, 5 parts sodium carbonate, and 5 parts trisodium orthophosphate.

(5) 20 parts sodium tripolyphosphate, parts trisodium nitrilotriacetate monohydrate, and 5 parts sodium metasilicate.

(6) 30 parts sodium tripolyphosphate, 5 parts tetrasodium pyrophosphate, and 5 parts trisodium orthophosphate.

(7) 10 parts sodium tripolyphosphate, parts trisodium nitrilotriacetate monohydrate, and 10 parts sodium ethane-l-hydroxy-1,1-diphosphonate.

The corresponding potassium or mixtures of sodium and potassium salts can be substituted for the above builders with essentially equivalent detergency building. Similarly, sodium and potassium salts of phytic acid; methylene diphosphonic acid; substituted methylene diphosphonic acids (e.g., ethylidene, isopropylidene, benzylmethylidene and chloromethylidene diphosphonates); polyitaconic acid, polymaleic acid, polymesaconic acid, polyfumaric acid, polycitronic acid, and copolymers with themselves and other compatible monomers such as ethylene; and mixtures thereof can be substituted for part, or all, of the builder systems, either in the detergent granules or in particulate form in the added builder systems to achieve substantially the same results insofar as detergency building is concerned, and the resulting tablet cores can be improved by the coatings hereinafter described.

The above described mechanical mixes are tableted at pressures of about 100 p.s.i., 175 p.s.i., 250 p.s.i., 275 p.s.i. and 350 p.s.i., in tablet cores having a maximum diameter of about 5.71 cm. with the edges beveled at 30 angles. The tablet cores contain about 55 gm. of tablet mix.

These tablet cores are then uniformly coated by both spray-on and immersion processes with the following 12 aqueous solutions at a temperature of about F. to give a coating after drying and cooling, of about 0.015 gm./em. for the spray-on process and about 0.03 gm./ cm. for the immersion process on an anhydrous basis. The undefined balance of each of the following aqueous solutions is water.

Percent Percent Coating Surfactant Surfac- Urea tant l Sodium lauryl sulfate 10 50 2 Dodecyl phenol (one mole) ethylene 10 00 oxide (10 moles) condensate. Polyethylene glycol (Molecular 33% 33% weight, about 4,000). Fatty alcohol (one mole; 0 4-018) 7 59 ethylene oxide (10 moles) condensate. Hydroxy sultaine 23 40 Hydroxy sultaine 5 50 Nonyl phenol (one mole) ethylene l0 oxide (12 moles) condensate. Polyethylene glycol (molecular 7 40 7 weight, about 6,000).

Nonyl phenol (one mole) ethylene 7 oxide (20 moles) condensate. Sodium lauryl sulfate 10 40 8 Nonyl phenol (one mole) ethylene 10 oxide (12 moles) condensate. Sodium lauryl sulfate G 50 9 Polyethylene glycol (molecular 12 weight, about 4,000

When the corresponding anhydrous coatings are applied in melt form (about 300 F.) by spraying or coating, substantially equivalent results are obtained in that the tablet cores are strengthened without appreciably affecting their quick-dissolving properties.

What is claimed is:

1. A quick-dissolving detergent tablet consisting essentially of a core of compressed detergent particles and a substantially uniform coating around said core consisting essentially of a urea-containing composition selected from the group consisting of (A) A solidified melt of -(1) Urea and (2) A material selected from the group consisting (a) Polyethylene glycol having a molecular weight of from about 500 to about 10,000; (b) Water soluble detergent surfactant having a long straight chain in its molecular structure, which Water soluble detergent surfactant is selected from the group consisting of (i) Water soluble salts of alkyl sulfates wherein the alkyl group contains from about 12 to about 18 carbon atoms;

(ii) The condensation product of a straight chain alcohol containing from about 12 to about 18 carbon atoms with at least about 8 moles of ethylene oxide per mole of alcohol;

(iii) The condensation product of an alkyl phenol wherein the alkyl group contains from about 8 to about 15 carbon atoms with at least about 8 moles of ethylene oxide per mole of alkyl phenol; and

(iv) A compound having the formula R2 R I l+CHz-CHOHCHzSOr wherein the R alkyl contains from about 12 to about 18 carbon atoms and the R and R alkyls each contain from 1 to about 3 carbon atoms; and (c) Mixtures of components (a) and (b);the ratio of urea to component (2) being in the range from about 1:1 to about 9: 1, the melt having been solidified while present on the surface of the detergent tablet in an amount to give a coating of from about .005 to about 0.1 gram per square centimeter of tablet surface area on an anhydrous basis; and

(B) A composition resulting from drying an aqueous mixture of (1) Urea;

(2) A material selected from the group consisting (a) Polyethylene glycol having a molecular weight of from about 500 to about 10,000;

(b) Water soluble deter-gent surfactant having a long straight chain in its molecular structure, which water soluble detergent surfactaut is selected from the group consisting of (i) Water soluble salts of alkyl sulfates wherein the alkyl group contains from about 12 to about 18 carbon atoms;

(ii) The condensation product of a straight chain alcohol containing from about 12 to about 18 carbon atoms with at least about 8 moles of ethylene oxide per mole of alcohol;

(iii) The condensation product of an alkyl phenol wherein the alkyl group contains from about 8 to about 15 carbon atoms with at least about 8 moles of ethylene oxide per mole of alkyl phenol; and

(iv) A compound having the formula wherein the R alkyl contains from about 12 to about 18 carbon atoms and the R and R alkyls each contain from 1 to about 3 carbon atoms; and (c) Mixtures of components (a) and (b); and (3) Water: the ratio of urea to component (2) being in the range from about 1:1 to about 9:1 and the ratio of water to components (1) and (2) being in the range from about 3 :1 to about 1:25, the aqueous mixture having been dried while present on the surface of the detergent tablet in an amount to give a coating of from about .005 to about 0.1 gram per square centimeter of tablet surface area on an anhydrous basis.

2. The table-t of claim 1 wherein the molecular weight of said polyethylene glycol is from about 3,000 to about 7,500.

3. The tablet of claim 1, wherein there is from about .025 to about .075 gram of coating per square centimeter on an anhydrous basis.

4. The tablet of claim 1, which was compressed at a pressure of from about 100 to about 350 p.s.i.g.

5. The process of coating a quick-dissolving detergent tablet consisting essentially of the steps of (A) Preparing a melt of (l) Urea and (2) A material selected from the group consisting (a) Polyethylene glycol having a molecular weight of from about 500 to about 10,000; (b) Water soluble detergent surfactant having a long straight chain in its molecular structure, which water soluble detergent surfactant is selected from the group consisting of (i) Water soluble salts of alkyl sulfates wherein the alkyl group contains from about 12 to about 18 carbon atoms; (ii) The condensation product of a straight chain alcohol containing from about 12 to about 18 carbon atoms with at least about 8 moles of ethylene oxide per mole of alcohol;

(iii) The condensation product of an alkyl phenol wherein the alkyl group contains from about 8 to about 15 carbon atoms with at least about 8 moles of ethylene oxide per mole of alkyl phe 1101; and

(iv) A compound having the formula R2 R I I -CH2CHOHCH2S Oawherein the R alkyl contains from about 12 to about 18 carbon atoms and the R and R alkyl-s each contain from about 1 to about 3 carbon atoms; and (c) Mixtures of components (a) and (b); the ratio of urea to component (2) being in the range from about 1:1 to about 9:1, and the temperature of the melt being from about 275 F. to about 350 F.;

(B) Applying from about .005 to about 0.1 gram per square centimeter of said melt to the Surface of said detergent tablet; and

-(C) solidifying said melt.

6. The process of claim 5 wherein the melt is applied to the surface of said detergent tablet by spraying said melt on said surface.

7. The process of claim 5 wherein the melt is applied to the surface of said detergent tablet by dipping said tablet in said melt.

8. The process of coating a quick-dissolving detergent tablet consisting essentially of the steps of '(A) Preparing an aqueous mixture of (1) Water, (2) Urea and (3) A material selected from the group consisting (a) Polyethylene glycol having a moecular weight of from about 500 to about 10,000; (b) Water soluble detergent surfactant having a long straight chain in its molecular structure, which water soluble detergent surfactant is selected from the group consisting of (i) Water soluble salts of alkyl sulfates wherein the alkyl group contains from about 12 to about 18 carbon atoms;

(ii) The condensation product of a straight chain alcohol containing from about 12 to about 18 carbon atoms with at least about 8 moles of ethylene OX- ide per mole of alcohol;

(iii) The condensation product of an alkyl phenol wherein the alkyl group contains from about 8 to about 15 carbon atoms with at least about 8 moles of ethylene oxide per mole of alkyl phenol; and

(iv) A compound having the formula wherein the R alkyl contains from about 12 to about 18 carbon atoms and the R and R alkyls each contain from 1 to about 3 carbon atoms; and (c) Mixtures of components (a) and (b); the ratio of urea to component (3) being in the range from about 1:1 to about 9:1, and the ratio of water to 15 components (2) and (3) being in the range from about 3:1 to about 1:2.5;

(B) Applying said aqueous mixture to the surface of the detergent tablet consisting essentially of compressed detergent particles in an amount sufficient to give a coating of from about .005 to about 0.1 gram per square centimeter of tablet surface area on an anhydrous basis; and

(C) Drying said aqueous mixture.

9. The process of claim 8 wherein the ratio of water to components (2) and (3) is from about 1:1 to about 1 1.5, and the aqueous mixture is a solution.

10. The process of claim 8 wherein the aqueous mixture is a solution and the solution is applied to the detergent tablet by dipping the detergent tablet in the aqueous mixture 11. The process of claim 8 wherein the aqueous mixture is a solution, the temperature of which solution is sufficiently high that the solution is a single phase, but not more than about 210 F.

References Cited UNITED STATES PATENTS LEON D. ROSDAL, Primary Examiner.

S. E. DARDEN, Assistant Examiner. 

1. A QUICK-DISSOLVING DETERGENT TABLET CONSISTING ESSENTIALLY OF A CORE OF COMPRESSED DETERGENT PARTICLES AND A SUBSTANTIALLY UNIFORM COATING AROUND SAID CORE CONSISTING ESSENTIALLY OF A UREA-CONTAINING COMPOSITION SELECTED FROM THE GROUP CONSISTING OF (A) A SOLIDIFIED MELT OF (1) UREA AND (2) A MATERIAL SELECTED FROM THE GROUP CONSISTING OF (A) POLYETHYLENE GLYCOL HAVING A MOLECULAR WEIGHT OF FROM ABOUT 500 TO ABOUT 10,000; (B) WATER SOLUBLE DETERGENT SURFACTANT HAVING A LONG STRAIGHT CHAIN IN ITS MOLECULAR STRUCTURE, WHICH WATER SOLUBLE DETERGENT SURFACTANT IS SELECTED FROM THE GROUP CONSISTING OF (I) WATER SOLUBLE SALTS OF ALKYL SULFATES WHEREIN THE ALKY GROUP CONTAINS FROM ABOUT 12 TO ABOUT 18 CARBON ATOMS; (II) THE CONDENSATION PRODUCT OF A STRAIGHT CHAIN ALCOHOL CONTAINING FROM ABOUT 12 TO ABOUT 18 CARBON ATOMS WITH AT LEAST ABOUT 8 MOLES OF ETHYLENE OXIDE PER MOLE OF ALCOHOL; (III) THE CONDENSATION PRODUCT OF AN ALKYL PHENOL WHEREIN THE ALKYL GROUP CONTAINS FROM ABOUT 8 TO ABOUT 15 CARBON ATOMS WITH AT LEAST ABOUT 8 MOLES OF ETHYLENE OXIDE PER MOLE OF ALKYL PHENOL; AND (IV) A COMPOUND HAVING THE FORMULA 